The invention relates to a drum with a drum closure provided in a drum wall comprising an insert for a shut-off cap or plug which can be placed in the insert which insert is situated in a collar on the drum wall pointing towards the outside of the drum and has a first flange which rests against the inside of the drum wall and a second flange which is flanged radially outwards over the collar and also a sealing ring which is wedged between the first flange and the inside of the drum wall.
Such a drum is generally known. When the insert is being fitted in the drum wall the first flange is firmly pressed against the drum wall in such a way that the sealing ring is compressed to provide the required seal. The second flange is then flange over the collar. The result of this is that the sealing ring can be held firmly wedged with pre-tension between the first flange and the drum wall.
The required sealing of the closure is maintained so long so the sealing ring can be held firmly wedged in this way. However, as soon as the wedging reduces, the risk of leakages occurs. Such a reduction of the wedging can occur if the drum falls from a certain height onto a hard surface with the closure down. The insert which projects relative to the drum wall is pressed inwards in this case which results in the first flange and the drum wall being pressed apart.
As a result of its elasticity the sealing ring can absorb deformations up to a certain level without leakages occurring. However, if the deformations become too great, as is mostly the case when the drum falls, the seal cannot still be guaranteed. The objective of the invention is therefore to equip a drum of the type described above with an improved closure in such a way that even if the drum falls on the closure the seal will still remain.
This object is achieved through the fact that an additional seal, which may or may not be connected to the sealing ring, is provided between the collar and the insert lying opposite. As a result of the position of the additional seal between the collar and the insert it is ensured that the sealing is maintained even if the insert is pressed inwards relative to the collar as the result of a fall.
The additional seal can be obtained in various ways. According to a first possibility, the additional seal is a loose second sealing ring which is compressed in the radial direction between collar and insert. In this case the insert can slide inwards along with the sealing ring without the pretension with which it is held wedged relative to the collar decreasing. Thus even quite large deformations of the drum wall and the insert can be absorbed without leakages being able to occur.
According to a second possibility, the additional seal is a loose second sealing ring which is compressed in the axial direction between the end face of the collar and the flanged part of the second flange of the insert. If the drum now falls with its closure onto a hard surface, the second sealing ring is compressed to a greater extend. The seal between insert and collar is therefore also maintained in this case.
In the case of the embodiments described above the two sealing rings can be made of different materials. This means that the original sealing ring which is in contact with the drum contents can be made of a material suitable for that purpose. On the other hand, a material which is capable of undergoing great compression can be selected for the additional sealing ring. It is also important here that this material should have a low coefficient of friction with regard to the metal collar and the insert in view of the great displacements which occur when they are compressed in the radial direction.
If the choice of material is not important, according to a third embodiment, the additional seal can be a sealing ring part which is fixed to the sealing ring and lies on the side of the sealing ring facing away from the first flange. In that case the whole sealing ring is preferably made of material with a low coefficient of friction.
An embodiment of the invention will be explained in greater detail below with reference to an exemplary embodiment shown in the figures.